1. Technical Field
This present application relates to a method and device for the controlled foaming of a product introduced in bottles or similar containers.
2. Background Information
Background information is for informational purposes only and does not necessarily admit that subsequently mentioned information and publications are prior art.
In the beverage industry, bottles, kegs or similar containers that have been filled in a filling machine with a bulk material, usually with a liquid that comprises carbon dioxide or an otherwise effervescent liquid, must or should be pressurized with a liquid foaming medium under pressure. The objective is to foam the liquid in the individual container to thereby displace any air or atmospheric oxygen that is present in the container above the level of the liquid and to restrict or minimize any adverse effect of oxygen on the liquid or its shelf life and taste. The liquid foaming medium used can thereby be water, for example, and usually heated water, for example. For the introduction of the foaming medium, at least one injector nozzle is used to which the foaming medium is fed under pressure and underneath which the containers filled with the liquid being bottled are carried on a conveyor line between a filling machine and a capping or closing machine which is downstream of this bottling machine in the production line. The introduction or injection of the foaming fluid must or should be done with due consideration given to product-specific parameters and as a function of the output of the production line, i.e. as a function of the number of containers treated with the foaming medium per unit of time, so that on one hand a sufficiently strong foaming is achieved, and on the other hand, gushing is restricted or minimized. It is also desired to perform the introduction of the foaming medium in a sterile environment.
The amount of energy introduced into the container for the foaming is a function of a number of different parameters such as, for example, the temperature and the quantity of the foaming medium introduced into the individual container as well as the injection pressure with which this medium is injected into the container. The duration of the injection must or should also be taken into consideration.
In methods and devices for foaming, the injection pressure and the volume flow of the foaming medium are fixed for the respective liquid being bottled and for a specified production rate of the filling machine and/or of the production line. Fluctuations in the production rate of the production line, however, therefore result in an unsatisfactory foaming of the liquid in the containers, i.e. either insufficient foaming or gushing.
Some devices are used for the controlled feed of an inert gas, for example CO2 gas, to beverage cans during the closing process to improve the shelf life of the product by displacing the air and atmospheric oxygen above the level of the liquid. The quantity of gas injected is regulated as a function of the speed with which the cans are closed.
Some devices and methods with a variable injection height or pressure in the injector nozzle are used to achieve an optimum foaming result. Some use a piston pump arrangement activated by compressed air or a pump driven by an electric motor and a dosing valve control system to optimize the foaming. Some devices utilize a piston system with a pressure booster.
With these systems, however, which generally function well, one remaining problem is that primarily on high-capacity or high-speed filling and closing machines, a relatively large quantity of fluid should be injected to essentially ensure or promote complete foaming. It is also not possible to react optimally, suitably and quickly to changes in the speed of the production process over its entire range, from startup conditions to maximum production.